Your ability to build muscle can be affected by a variety of factors: genetics, diet, workouts, hormones, age, and even gender.
More women are expressing an interest in lifting weights as they’re losing their fear of getting “bulky” from strength training. They’re also embracing the many health benefits that come from weight training.
If one of your goals this year is to build more muscle, there are ways to improve your chances of gaining more muscle and strength. But first, it’s important to understand what determines your muscle-building ability.
With the help of fitness experts and scientific research, we break down how muscle growth varies, but also what changes you can make to get those gains. Read on to find out what factors influence your ability to build muscle and how you can make them work in your favor. It may even explain why your friend who barely works out effortlessly has defined arms and abs.
Genetics plays an important role in determining your body’s ability to put on muscle (and its limitations), partly by influencing your hormonal and muscular make-up. But they’re not the end-all, be-all.
Hormones
Anabolic hormones — consisting of growth hormone, estrogen, insulin, and testosterone — are key for muscle building. Contrary to popular belief, estrogen and testosterone are both important for muscle structure and function.
Testosterone is responsible for muscle growth, while estrogen improves muscle mass and strength, as well as growing the collagen of connective tissues, such as your bones, ligaments and tendons. Women typically produce more estrogen and less testosterone than men, which is why men often have an easier time with visible muscle growth. (The same seems to be true for transgender people who take hormone replacement therapy.)
Testosterone is an anabolic hormone and 10 times higher in men which can benefit muscle growth goals, according to experts. Testosterone helps release growth hormones, which stimulate tissue growth, and it connects with nuclear receptors in DNA, which causes protein synthesis (or muscle growth).
As both men and women age, the reduction of both testosterone and estrogen hormones can result in the breakdown of muscle. Other aspects that can diminish your muscles are fluctuating hormones, such as adrenaline, cortisol, and glucagon, which prevent them from growing.
That’s why it’s important to monitor your day-to-day stress, sleep, and diet, since these impact those hormones and in turn affect your ability to progress.
Muscle Fibers
Another thing that can influence how well you put on muscle is your fast-twitch and slow-twitch muscle fibers. Skeletal muscles are composed of both of these fibers, which serve different purposes and determine your potential athletic ability.
Fast-twitch muscle fibers are large and generate quick bursts of energy that are good for exercises such as sprinting, jumping, powerlifting, and strength training. On the other hand, slow-twitch muscle fibers are smaller and intended to help you sustain long periods of cardio such as long-distance running, swimming, cycling, and any type of endurance training.
We all have fast-twitch and slow-twitch muscle fibers, but genetically some people may be predisposed to have more of one than the other. And fast-twitch fibers are the ones that you need for sizable muscle growth.
Different muscle fiber characteristics, Type I and II, slow and fast twitch respectively can both increase in size, but the latter can have more growth potential.
Research has found that two genes, known as the ACTN3 gene and the ACE gene, heavily influence which muscle fibers we have more of.
The ACTN3 gene helps create a protein that is found in fast-twitch muscle fibers, for example, while a genotype known as 577XX can occur across both genes, reducing fast-twitch muscle fibers and increasing slow-twitch fibers. On the other hand, the 577RR genotype is linked to a greater presence of fast-twitch muscle fibers.
Tendon length can also determine how big your muscles get. Tendons vary per person, but it’s been found that having shorter tendons allow you to gain bigger muscles, while longer tendons make it harder to do so.
Still, it’s not all about how you’re born. There is an upper limit to a muscle’s fiber size; however, don’t forget that without proper and consistent training the muscle’s true potential won’t be realized. So just because your genetics say that you can put on muscle easier, if you don’t put in the work, there won’t be anything to show for it.
It’s impossible to ignore nutrition when discussing muscle mass. How you eat can make a big difference in how well your body puts on and maintains muscle. Muscle is a very expensive tissue to maintain. You have to be intentional about not only putting it on but also maintaining it.
Eating enough calories and protein helps with muscle recovery and growth after a workout. Muscle is made up of protein, and eating adequate protein after strength training is essential to limit muscle protein breakdown and assist with muscle synthesis (growth of new muscle).
Individuals who strength train require more protein than their non-training counterparts. Older adults will require more in general, but even more so if they strength train. Similarly, if you want to put on muscle, you’ll need to add more calories to your diet.
Well-trained individuals consume an additional 500 to 1,000 calories per day, and untrained individuals, new to strength training, eating up to an additional 2000 calories per day can show positive changes in muscle mass. In my day-to-day work with clients, in many cases, 15 to 18 calories per pound have been supportive of client hypertrophy goals. (Muscular hypertrophy refers to growing your muscles through exercise.)
Of the 20 amino acids found in protein, leucine is the most essential to promote muscle growth — and the body cannot produce it. Three to four grams of leucine [or 6 to 8 ounces of animal protein] can promote maximal protein synthesis.
If you’re a vegetarian, you will need to strategically prepare your meals ahead of time to achieve this, because plant-based proteins may only provide 25 to 60% of the recommended amount of leucine.
Some women who are having a hard time building muscle may be self-sabotaging their potential without even realizing it. Many women are caught in the dieting mindset of always wanting to be smaller and weigh less on the scale, which isn’t conducive to building muscle.
A lot of women are scared to see the scale go up a bit because adding muscle means you’re going to be adding weight. I have so many clients that weigh more now but look completely different with more muscle on their bodies. If you do allow yourself to gain that weight for muscle building, you can change the look and feel of your body, and the number on the scale will become irrelevant.
Simple nutrition strategies such as meal planning, meal scheduling, budgeting, and supplementation can be implemented to overcome challenges such as figuring out your food intake. If you aren’t sure where to begin, it’s a good idea to consult with a sports dietitian who can set you on the right path to your goals.
Feel free to address our experts to ask any additional questions.